1. Field of the Invention
This invention relates to a flat plate type rotary transformer, and more particularly pertains to a flat plate type rotary transformer in which the gap between the magnet core on the primary side and the magnet core on the secondary side is controlled so as to be a predetermined size with high accuracy.
2. Description of the Prior Art
A rotary transformer is characterized by its primary side magnet core and the secondary side magnet core being magnetically coupled without touching each other for which reason it is finding uses, for example, in rotary drum type magnet recording and playing devices, etc.
FIG. 1 is a longitudinal sectional view of a conventional flat plate type rotary transformer, in which magnet cores 1 and 2 are of magnetic material as, for example, ferrite; coils 3-6 are provided in the opposed faces of cores 1 and 2; lead wires 7-10 extend from the aforementioned coils; and grooves 11 and 12 are provided in the opposed faces between the coils for the prevention of interference. As a current is caused to flow in the coil 3, an induced current flows in the coil 4, and likewise, current in coil 5 induces a current in the coil 6. Because the magnetic circuit includes a clearance having a large magnetic resistance as a part thereof, the rate of change of loss due to the clearance, and thus a decrease in the transmission efficiency, is very large, as shown in FIG. 2.
Accordingly, to obtain a rotary transformer with uniform characteristics, it is quite essential to establish the desired gap between the two magnet cores with a high degree of accuracy.